A gentleman’s sweep by the hated Boston Celtics in 2018. A four-bounce, buzzer-beating heartbreaker to the Toronto Raptors a season later.

Sunday’s 103-96 Game 7 loss to the Atlanta Hawks in the Eastern Conference semifinals added to the list of 76ers disappointments.

The Sixers were booed off the court in the final seconds. One fan even threw an object onto the Wells Fargo Center court late in the game.

Yes, this was a bad loss. One that stung worse than the previous defeats because, as the top seed, the Sixers were expected to advance to the conference finals.

“It sucks to come up short once again,” said Joel Embiid, the only Sixer who wasn’t booed. “There’s a lot of stuff that happened. You know, it just felt like this was going to be our year. But whether it was COVID and injuries and stuff, it just sucks.”

They struggled down the stretch Sunday night, especially after Hawks guard Trae Young woke up.

Young had a tough shooting night, missing 18 of his first 22 shot attempts. However, the Hawks point guard made a 13-footer to give Atlanta an 86-84 lead with 5 minutes, 11 seconds remaining. Then he assisted on an alley-oop to Clint Capela with 3:08 left to put the Hawks up, 90-87. Young then drained a 29-foot three-pointer over Ben Simmons to extend the lead to 93-87 at the 2:31 mark.

» READ MORE: Ben Simmons disappeared from Game 7. The Sixers’ faith in him might be gone, too. | David Murphy

With the Sixers down, 93-89, the Hawks went to a hack-a-Ben. Simmons made 1 of 2 foul shots after being intentionally fouled to make it a 93-90 game. Then a layup by Tobias Harris pulled the Sixers within 93-92 with 1:10 left.

But Matisse Thybulle fouled Kevin Huerter on a three-point attempt with 54 seconds left. Thybulle put his head in his hands after the foul was called. The Hawks guard made all three foul shots to give Atlanta a 96-92 lead. On the ensuing possession, an Embiid turnover, his eighth of the game, led to a breakaway layup by Danilo Gallinari at the other end to make it 98-92.

After a Shake Milton acrobatic basket, Young added a foul shot to put the Hawks up, 99-94. Then Gallinari added a pair of free throws to give the Hawks a 101-94 lead with 25.7 seconds left.

The Sixers were also doomed by committing 17 turnovers.

Young finished with 21 points on 5-for-23 shooting to go with 10 assists, while Huerter had a team-high 27 points. The 6-foot-7 Huerter repeatedly took advantage of the mismatch of being guarded by the 6-0 Seth Curry. He made 10 of 18 shots.

Embiid led the Sixers with 31 points and 11 rebounds to go with the eight turnovers. Harris had 24 points and 14 rebounds, but made just 8 of 24 shots.

Simmons finished with five points, 13 assists, and eight rebounds. He attempted just four shots, making two. For the fourth straight game, he did not attempt a shot in the fourth quarter. Simmons played timid, like someone fearful of having to go to the foul line.

That became apparent with 3:29 remaining and the Sixers trailing, 88-86. He drove to the basket past Gallinari, but he passed up an open dunk underneath the basket, dishing the ball to Thybulle, who was fouled by John Collins. Thybulle made 1 of 2 free throws.

Simmons’ actions drew boos from the crowd.

Doc Rivers was asked after the game whether Simmons can be the point guard on a championship team.

“I don’t know that question or the answer to that right now,” the coach said. “So I don’t know the answer to that.”

The Sixers will obviously explore the Simmons trade market this offseason.

They tried to trade him to the Houston Rockets in exchange for James Harden earlier in the season. But the Rockets opted instead to trade Harden to the Brooklyn Nets. The Sixers also tried to acquire Kyle Lowry in a trade with the Raptors to help Simmons with the ballhandling duties.

Simmons was asked whether he thinks he played last minutes in Philadelphia.

“I feel like we just lost Game 7,” Simmons said. “That was about it.”

Asked if he wants to stay in Philly, Simmons said he loves being here.

“I love this organization,” he said. “The fans are great people. I had a bad series. I expect that [criticism]. It’s Philly.”

Getting out of the second round wasn’t their ultimate goal. Rivers stressed that on the eve of this series.

But an inability to get beyond the second round led to general manager Elton Brand saying after last season that “The Process” was a failure.

The Sixers lost in the second round to the Celtics in five games in 2018. A season later, Kawhi Leonard’s 15-foot fadeaway jumper at the buzzer lifted the Raptors to a 92-90 Game 7 victory. Then last season, the Sixers were swept by the Celtics in the first round.

Those successive endings led to the Sixers making a head-coaching change and tweaking the front office, which brought in Daryl Morey as president of basketball operations.

So this postseason series was bigger than what Rivers will admit.

Sure, the Sixers finished with the conference’s No. 1 seed for the first time since 2001. Yes, Embiid was the MVP runner-up and Simmons the runner-up for defensive player of the year. But none of that matters after losing to the Hawks Sunday night.

“It’s really disappointing as players and, obviously, the talent level we had in this group and our expectation as a whole as a group,” Harris said. “In these moments, you obviously have to learn from them as well and push forward on them.

“We really let slip away an opportunity. And that’s something that stings the most.”

One can argue the Sixers are the equivalent of a polished 1976 Chevy Chevette. Sure, it has a brand-new paint job, new rims, and tires. But it was the same old Chevette with high mileage and engine trouble.

But it was not supposed to be this way, with the Sixers looking to win a second-round series for just the second time in the franchise’s last 11 appearances, dating to 1986. They beat the Raptors in seven games in the second round in 2001 en route to losing in the NBA Finals.

On Sunday, the Sixers blew an opportunity to do something really big with some of the other favorites already being eliminated.

“Definitely, it’s Game 7,” Simmons said. “We didn’t get past this round. So obviously it hurts.”

On Sunday night, Embiid was feeling it early on. The center flexed on a Hawks defender after muscling his way to a clutch basket. Then he gave an “I Got This” stare to the fans at the end of the first quarter.

Yes, the four-time All-Star was in a groove.

Embiid finished the quarter with nine points on 4-for-5 shooting to go with four rebounds. His weakness came at the foul line, where he made just 3 of 6 shots. Harris was the Sixers’ second-leading scorer with seven points on 3-for-7 shooting. With those two leading the way, the Sixers took a 28-25 lead into the second quarter.

The second quarter was one Harris and the Sixers would like to have back. The Sixers were outscored, 23-18, thanks in large part to horrid shooting. Harris missed all three of his shots to score one point in the quarter. As a whole, the Sixers shot 35% and went 1-for-7 from the three-point line.

Seth Curry (16 points) kept them in the game, however, by scoring eight points on 3-for-5 shooting in the second. He also made their only three-pointer.

The Hawks went on to outscore the Sixers, 28-25, in the third quarter to take a 76-71 cushion into the fourth.

Sunday’s game marked Rivers’ NBA all-time-leading 15th Game 7 as a coach. The 59-year-old is 6-9 in Game 7s, including a 6-5 home record.